108 KiB
User Guide
Introduction
Mongoose is a networking library for C/C++. It implements event-driven, non-blocking APIs for TCP, UDP, HTTP, WebSocket, MQTT. It connects devices and brings them online. Since 2004, a number of open source and commercial products have utilized it. It even runs on the International Space Station! Mongoose makes embedded network programming fast, robust, and easy.
Mongoose has two basic data structures:
struct mg_mgr
- An event manager that holds all active connectionsstruct mg_connection
- A single connection descriptor
Connections could be listening, outbound, or inbound. Outbound
connections are created by the mg_connect()
call. Listening connections are
created by the mg_listen()
call. Inbound connections are those accepted by a
listening connection. Each connection is described by a struct mg_connection
structure, which has a number of fields. All fields are exposed to the
application by design, to give an application full visibility into
Mongoose's internals.
2-minute integration guide
In order to integrate Mongoose into an existing C/C++ application or firmware, please use the following steps:
Step 1. Copy mongoose.c and mongoose.h into the source code tree
Step 2. Add the following lines in your main.c
file:
#include "mongoose.h"
...
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
struct mg_http_serve_opts opts = {.root_dir = "."}; // Serve local dir
if (ev == MG_EV_HTTP_MSG) mg_http_serve_dir(c, ev_data, &opts);
}
...
int main() {
...
struct mg_mgr mgr;
mg_mgr_init(&mgr);
mg_http_listen(&mgr, "0.0.0.0:8000", fn, NULL); // Create listening connection
for (;;) mg_mgr_poll(&mgr, 1000); // Block forever
}
Step 3. Add mongoose.c
to the build and recompile - and that is it!
mg_mgr_poll()
iterates over all connections, accepts new connections, sends and
receives data, closes connections, and calls event handler functions for the
respective events.
Each connection has two event handler functions: c->fn
and c->pfn
. The
c->fn
is a user-specified event handler function. The c->pfn
is a
protocol-specific handler function that is set implicitly. For example, a
mg_http_listen()
sets c->pfn
to a Mongoose's HTTP event handler. A
protocol-specific handler is called before a user-specific handler. It parses
incoming data and may invoke protocol-specific events like MG_EV_HTTP_MSG
.
NOTE:
Since Mongoose's core is not protected against concurrent accesses, make
sure that all mg_*
API functions are called from the same thread or RTOS
task.
Send and receive buffers
Each connection has a send and receive buffer:
struct mg_connection::send
- Data to be sent to a peerstruct mg_connection::recv
- Data received from a peer
When data arrives, Mongoose appends received data to the recv
and triggers a
MG_EV_READ
event. The user may send data back by calling one of the output
functions, like mg_send()
, mg_printf()
or a protocol-specific function like
mg_ws_send
. Output functions append data to the send
buffer. When Mongoose
successfully writes data to the socket, it discards data from struct mg_connection::send
and sends an MG_EV_WRITE
event.
Event handler function
Each connection has an event handler function associated with it, which must be implemented by the user. Event handler is the key element of Mongoose, since it defines the connection's behavior. See below for an example of an event handler function:
// Event handler function defines connection's behavior
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_READ) {
mg_send(c, c->recv.buf, c->recv.len); // Implement echo server
c->recv.len = 0; // Delete received data
}
}
struct mg_connection *c
- A connection that received an eventint ev
- An event number, defined in mongoose.h. For example, when data arrives on an inbound connection,ev
would beMG_EV_READ
void *ev_data
- Points to the event-specific data, and it has a different meaning for different events. For example, for anMG_EV_READ
event,ev_data
is anint *
pointing to the number of bytes received from a remote peer and saved into thec->recv
IO buffer. The exact meaning ofev_data
is described for each event. Protocol-specific events usually haveev_data
pointing to structures that hold protocol-specific informationvoid *fn_data
- A user-defined pointer for the connection, which is a placeholder for application-specific data. Thisfn_data
pointer is set during the*_listen()
or*_connect()
call, and it is stored in thec->fn_data
. Listening connections copy the value ofc->fn_data
to the newly accepted connection, so all accepted connections initially share the samefn_data
pointer. It is fine to update/replace that pointer for any connection at any time by settingc->fn_data = new_value;
Events
Below is the list of events triggered by Mongoose, taken as-is from mongoose.h
.
For each event, a comment describes the meaning of the ev_data
pointer passed
to an event handler:
enum {
MG_EV_ERROR, // Error char *error_message
MG_EV_OPEN, // Connection created NULL
MG_EV_POLL, // mg_mgr_poll iteration uint64_t *milliseconds
MG_EV_RESOLVE, // Host name is resolved NULL
MG_EV_CONNECT, // Connection established NULL
MG_EV_ACCEPT, // Connection accepted NULL
MG_EV_READ, // Data received from socket struct mg_str *
MG_EV_WRITE, // Data written to socket long *bytes_written
MG_EV_CLOSE, // Connection closed NULL
MG_EV_HTTP_MSG, // HTTP request/response struct mg_http_message *
MG_EV_HTTP_CHUNK, // HTTP chunk (partial msg) struct mg_http_message *
MG_EV_WS_OPEN, // Websocket handshake done struct mg_http_message *
MG_EV_WS_MSG, // Websocket msg, text or bin struct mg_ws_message *
MG_EV_WS_CTL, // Websocket control msg struct mg_ws_message *
MG_EV_MQTT_CMD, // MQTT low-level command struct mg_mqtt_message *
MG_EV_MQTT_MSG, // MQTT PUBLISH received struct mg_mqtt_message *
MG_EV_MQTT_OPEN, // MQTT CONNACK received int *connack_status_code
MG_EV_SNTP_TIME, // SNTP time received uint64_t *milliseconds
MG_EV_USER, // Starting ID for user events
};
Connection flags
struct mg_connection
has a bitfield with connection flags. Flags are binary:
they can be either 0 or 1. Some flags are set by Mongoose and must be not
changed by an application code. For example, the is_udp
flag tells the application if
that connection is UDP or not. Some flags can be changed by application, for
example, the is_draining
flag, if set by an application, tells Mongoose to send
the remaining data to a peer, and when everything is sent, close the connection.
NOTE: User-changeable flags are:
is_hexdumping
, is_draining
, is_closing
.
This is taken from mongoose.h
as-is:
struct mg_connection {
...
unsigned is_listening : 1; // Listening connection
unsigned is_client : 1; // Outbound (client) connection
unsigned is_accepted : 1; // Accepted (server) connection
unsigned is_resolving : 1; // Non-blocking DNS resolv is in progress
unsigned is_connecting : 1; // Non-blocking connect is in progress
unsigned is_tls : 1; // TLS-enabled connection
unsigned is_tls_hs : 1; // TLS handshake is in progress
unsigned is_udp : 1; // UDP connection
unsigned is_websocket : 1; // WebSocket connection
unsigned is_hexdumping : 1; // Hexdump in/out traffic
unsigned is_draining : 1; // Send remaining data, then close and free
unsigned is_closing : 1; // Close and free the connection immediately
unsigned is_full : 1; // Stop reads, until cleared
unsigned is_resp : 1; // Response is still being generated
unsigned is_readable : 1; // Connection is ready to read
unsigned is_writable : 1; // Connection is ready to write
};
Best practices
- If you need to perform any sort of initialisation of your connection,
do it by catching
MG_EV_OPEN
event. That event is sent immediately after a connection has been allocated and added to the event manager, but before anything else:static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) { if (ev == MG_EV_OPEN) { ... // Do your initialisation }
- If you need to keep some connection-specific data, you have two options.
First, use
c->fn_data
pointer. That pointer is passed to the event handler as last parameter:
Another option is to usestatic void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) { if (ev == MG_EV_OPEN) { c->fn_data = malloc(123); // Change our fn_data } else if (ev == MG_EV_CLOSE) { free(fn_data); // Don't forget to free! } ... } // Every accepted connection inherit NULL pointer as c->fn_data, but we change // it per-connection to something else mg_http_listen(&mgr, "http://localhost:1234", fn, NULL);
c->label
buffer, which can hold some amount of connection-specific data without extra memory allocation:static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) { if (ev == MG_EV_WS_OPEN) { c->label[0] = 'W'; // Established websocket connection, store something ...
- If you need to close the connection, set
c->is_draining = 1;
in your event handler function. That tells the event manager to send all remaining data in a send buffer ("drain" the connection), then close the connection. If you need to close the connection immediately without draining, usec->is_closing = 1;
- Use
mg_http_reply()
function to create HTTP responses. That function properly sets theContent-Length
header, which is important. Of course you can create responses manually, e.g. withmg_printf()
function, but be sure to set theContent-Length
header:
Alternatively, use chunked transfer enconding:mg_printf(c, "HTTP/1.1 200 OK\r\Content-Length: %d\r\n\r\n%s", 2, "hi");
NOTE: if you are not usingmg_printf(c, "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n"); mg_http_printf_chunk(c, "%s", "foo"); mg_http_printf_chunk(c, "%s", "bar"); mg_http_printf_chunk(c, ""); // Don't forget the last empty chunk
mg_http_reply()
ormg_http_*_chunk()
, make sure to setc->is_resp = 0;
when your event handler finished writing response. - On embedded environment, make sure that serving task has enough stack:
give it 2k for simple RESTful serving, or 4-8k for complex dynamic/static
serving. In certain environments, it is necessary to adjust heap size, too.
By default, IO buffer allocation size
MG_IO_SIZE
is 2048: change it to 512 to trim run-time per-connection memory consumption.
Build options
Mongoose source code ships in two files:
- mongoose.h - API definitions
- mongoose.c - Implementation
Therefore, to integrate Mongoose into an application, simply copy these two
files to the application's source tree. The mongoose.c
and mongoose.h
files
are actually an amalgamation - non-amalgamated sources can be found at
https://github.com/cesanta/mongoose/tree/master/src
Mongoose has two types of build constants (preprocessor definitions) that
affect the build: a target architecture, and tunables. In order to set the
option during build time, use the -D OPTION
compiler flag:
$ cc app0.c mongoose.c # Use defaults!
$ cc app1.c mongoose.c -D MG_ENABLE_IPV6=1 # Build with IPv6 enabled
$ cc app2.c mongoose.c -D MG_ARCH=MG_ARCH_FREERTOS_LWIP # Set architecture
$ cc app3.c mongoose.c -D MG_ENABLE_SSI=0 -D MG_IO_SIZE=8192 # Multiple options
The list of supported architectures is defined in the arch.h header file. Normally, there is no need to explicitly specify the architecture. The architecture is guessed during the build, so setting it is not usually required.
Name | Description |
---|---|
MG_ARCH_UNIX | All UNIX-like systems like Linux, MacOS, FreeBSD, etc |
MG_ARCH_WIN32 | Windows systems |
MG_ARCH_ESP32 | Espressif's ESP32 |
MG_ARCH_ESP8266 | Espressif's ESP8266 |
MG_ARCH_FREERTOS_LWIP | All systems with FreeRTOS kernel and LwIP IP stack |
MG_ARCH_FREERTOS_TCP | All systems with FreeRTOS kernel and FreeRTOS-Plus-TCP IP stack |
MG_ARCH_AZURERTOS | Microsoft Azure RTOS |
MG_ARCH_RTX_LWIP | Keil RTX with LWIP TCP/IP stack |
MG_ARCH_RTX | Keil RTX with MDK TCP/IP stack |
MG_ARCH_ZEPHYR | Zephyr RTOS |
MG_ARCH_TIRTOS | TI RTOS |
MG_ARCH_RP2040 | RP2040 SDK |
MG_ARCH_NEWLIB | Bare ARM GCC |
MG_ARCH_CUSTOM | A custom architecture, discussed in the next section |
The other class of build constants is defined in src/config.h together with their default values. These are tunables that include/exclude a certain functionality or change relevant parameters.
Here is a list of build constants and their default values:
Name | Default | Description |
---|---|---|
MG_ENABLE_SOCKET | 1 | Use BSD socket low-level API |
MG_ENABLE_MBEDTLS | 0 | Enable mbedTLS library |
MG_ENABLE_OPENSSL | 0 | Enable OpenSSL library |
MG_ENABLE_IPV6 | 0 | Enable IPv6 |
MG_ENABLE_MD5 | 0 | Use native MD5 implementation |
MG_ENABLE_SSI | 1 | Enable serving SSI files by mg_http_serve_dir() |
MG_ENABLE_CUSTOM_RANDOM | 0 | Provide custom RNG function mg_random() |
MG_ENABLE_CUSTOM_TLS | 0 | Enable custom TLS library |
MG_ENABLE_CUSTOM_MILLIS | 0 | Enable custom mg_millis() function |
MG_ENABLE_PACKED_FS | 0 | Enable embedded FS support |
MG_ENABLE_FATFS | 0 | Enable embedded FAT FS support |
MG_ENABLE_LINES | undefined | If defined, show source file names in logs |
MG_IO_SIZE | 2048 | Granularity of the send/recv IO buffer growth |
MG_MAX_RECV_SIZE | (3 * 1024 * 1024) | Maximum recv buffer size |
MG_MAX_HTTP_HEADERS | 40 | Maximum number of HTTP headers |
MG_HTTP_INDEX | "index.html" | Index file for HTML directory |
MG_FATFS_ROOT | "/" | FAT FS root directory |
NOTE: the MG_IO_SIZE
constant also sets
maximum UDP message size, see
issues/907 for details. If the
application uses large UDP messages, increase the MG_IO_SIZE
limit
accordingly.
Custom build
A custom build should be used for cases which is not covered by the existing architecture options (e.g., an embedded architecture that uses some proprietary RTOS and network stack). In order to build on such systems, follow the outline below:
- Add
-DMG_ARCH=MG_ARCH_CUSTOM
to your build flags. - Create a file called
mongoose_custom.h
, with defines and includes that are relevant to your platform. Mongoose usesbool
type,MG_DIRSEP
define, and optionally other structures likeDIR *
depending on the functionality you have enabled - see previous section. Below is an example:
#include <stdbool.h>
#include <stdarg.h>
#define MG_DIRSEP '/'
#define MG_INT64_FMT "%lld"
- This step is optional, and only required if you intend to use a custom TCP/IP stack. To do that, you should:
- Disable BSD socket API: in the
mongoose_custom.h
, add
#define MG_ENABLE_SOCKET 0
- Add an implementation of several internal API functions, like
mg_send()
,mg_mgr_poll()
, etc. For the reference, take a look at the stub "do nothing" implementation at test/mongoose_custom.c and the experimental builtin bare metal TCP/IP stack implementation at src/mip.c
Minimal HTTP server
This example is a simple HTTP server that serves both static and dynamic content:
#include "mongoose.h"
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
if (mg_http_match_uri(hm, "/api/hello")) {
mg_http_reply(c, 200, "", "%s\n", "hi"); // Serve dynamic content
} else {
struct mg_http_serve_opts opts = {.root_dir = "."}; // Serve
mg_http_serve_dir(c, ev_data, &opts); // static content
}
}
}
int main(int argc, char *argv[]) {
struct mg_mgr mgr;
mg_mgr_init(&mgr); // Init manager
mg_http_listen(&mgr, "http://0.0.0.0:8000", fn, &mgr); // Setup listener
for (;;) mg_mgr_poll(&mgr, 1000); // Event loop
mg_mgr_free(&mgr); // Cleanup
return 0;
}
Minimal TCP echo server
This example is a simple TCP echo server that listens on port 1234:
#include "mongoose.h"
static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_READ) {
mg_send(c, c->recv.buf, c->recv.len); // Echo received data back
mg_iobuf_del(&c->recv, 0, c->recv.len); // And discard it
}
}
int main(int argc, char *argv[]) {
struct mg_mgr mgr;
mg_mgr_init(&mgr); // Init manager
mg_listen(&mgr, "tcp://0.0.0.0:1234", cb, &mgr); // Setup listener
for (;;) mg_mgr_poll(&mgr, 1000); // Event loop
mg_mgr_free(&mgr); // Cleanup
return 0;
}
API Reference
Core
struct mg_addr
struct mg_addr {
uint16_t port; // TCP or UDP port in network byte order
uint32_t ip; // IP address in network byte order
uint8_t ip6[16]; // IPv6 address
bool is_ip6; // True when address is IPv6 address
};
This structure contains network address; it can be considered as a Mongoose equivalent for sockets sockaddr
structure.
struct mg_mgr
struct mg_mgr {
struct mg_connection *conns; // List of active connections
struct mg_dns dns4; // DNS for IPv4
struct mg_dns dns6; // DNS for IPv6
int dnstimeout; // DNS resolve timeout in milliseconds
unsigned long nextid; // Next connection ID
void *userdata; // Arbitrary user data pointer
};
Event management structure that holds a list of active connections, together with some housekeeping information.
struct mg_connection
struct mg_connection {
struct mg_connection *next; // Linkage in struct mg_mgr :: connections
struct mg_mgr *mgr; // Our container
struct mg_addr loc; // Local address
struct mg_addr rem; // Remote address
void *fd; // Connected socket, or LWIP data
unsigned long id; // Auto-incrementing unique connection ID
struct mg_iobuf recv; // Incoming data
struct mg_iobuf send; // Outgoing data
mg_event_handler_t fn; // User-specified event handler function
void *fn_data; // User-specified function parameter
mg_event_handler_t pfn; // Protocol-specific handler function
void *pfn_data; // Protocol-specific function parameter
char label[50]; // Arbitrary label
void *tls; // TLS specific data
unsigned is_listening : 1; // Listening connection
unsigned is_client : 1; // Outbound (client) connection
unsigned is_accepted : 1; // Accepted (server) connection
unsigned is_resolving : 1; // Non-blocking DNS resolve is in progress
unsigned is_connecting : 1; // Non-blocking connect is in progress
unsigned is_tls : 1; // TLS-enabled connection
unsigned is_tls_hs : 1; // TLS handshake is in progress
unsigned is_udp : 1; // UDP connection
unsigned is_websocket : 1; // WebSocket connection
unsigned is_hexdumping : 1; // Hexdump in/out traffic
unsigned is_draining : 1; // Send remaining data, then close and free
unsigned is_closing : 1; // Close and free the connection immediately
unsigned is_full : 1; // Stop reads, until cleared
unsigned is_resp : 1; // Response is still being generated
unsigned is_readable : 1; // Connection is ready to read
unsigned is_writable : 1; // Connection is ready to write
};
A connection - either a listening connection, or an accepted connection, or an outbound connection.
mg_mgr_init()
void mg_mgr_init(struct mg_mgr *mgr);
Initialize event manager structure:
- Set a list of active connections to NULL
- Set default DNS servers for IPv4 and IPv6
- Set default DNS lookup timeout
Parameters:
mgr
- a pointer tomg_mgr
structure that needs to be initialized
Return value: none
Usage example:
struct mg_mgr mgr;
mg_mgr_init(&mgr);
mg_mgr_poll()
void mg_mgr_poll(struct mg_mgr *mgr, int ms);
Perform a single poll iteration. For each connection in the mgr->conns
list:
- See if there is incoming data. If there is, read it into the
c->recv
buffer, sendMG_EV_READ
event - See if there is data in the
c->send
buffer, and write it, sendMG_EV_WRITE
event - If a connection is listening, accept an incoming connection if any, and send
MG_EV_ACCEPT
event to it - Send
MG_EV_POLL
event
Parameters:
mgr
- an event manager to usems
- a timeout in milliseconds
Return value: none
Usage example:
while (running == true) mg_mgr_poll(&mgr, 1000 /* 1 sec */);
mg_mgr_free()
void mg_mgr_free(struct mg_mgr *mgr);
Close all connections, and free all resources.
Parameters:
mgr
- an event manager to cleanup
Return value: none
Usage example:
struct mg_mgr mgr;
mg_mgr_init(&mgr);
while (running == true) mg_mgr_poll(&mgr, 1000); // Event loop
mg_mgr_free(&mgr);
mg_listen()
struct mg_connection *mg_listen(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fn_data);
Create a listening connection, append this connection to mgr->conns
.
Parameters:
mgr
- an event manager to useurl
- a URL. Specifies local IP address and port to listen on, e.g.tcp://127.0.0.1:1234
orudp://0.0.0.0:9000
fn
- an event handler functionfn_data
- an arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: created connection, or NULL
on error.
Usage example:
struct mg_connection *c = mg_listen(&mgr, "tcp://127.0.0.1:8080", fn, NULL);
mg_connect()
struct mg_connection *mg_connect(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fn_data);
Create an outbound connection, append this connection to mgr->conns
.
Parameters:
mgr
- An event manager to useurl
- A URL, specifies remote IP address/port to connect to, e.g.http://a.com
fn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: created connection, or NULL
on error.
Note: This function does not connect to peer, it allocates required resources and
starts connect process. Once peer is really connected, MG_EV_CONNECT
event is sent
to connection event handler.
Usage example:
struct mg_connection *c = mg_connect(&mgr, "http://example.org", fn, NULL);
mg_send()
int mg_send(struct mg_connection *c, const void *data, size_t size);
Append data
of size size
to the c->send
buffer. Return number of bytes
appended.
Note: This function does not push data to the network. It only appends data to
the output buffer. The data is being sent when mg_mgr_poll()
is called. If
mg_send()
is called multiple times, the output buffer grows.
Parameters:
c
- A connection pointerdata
- A pointer to data to append to the send buffersize
- A data size
Return value: true
if data appended successfully and false
otherwise
Usage example:
mg_send(c, "hi", 2); // Append string "hi" to the output buffer
mg_printf(), mg_vprintf()
int mg_printf(struct mg_connection *, const char *fmt, ...);
int mg_vprintf(struct mg_connection *, const char *fmt, va_list ap);
Same as mg_send()
, but formats data using printf()
semantics. Return
number of bytes appended to the output buffer.
NOTE: See mg_snprintf for the list of supported format specifiers
Parameters:
c
- a connection pointerfmt
- a format string inprintf
semantics
Return value: number of bytes appended to the output buffer.
Usage example:
mg_printf(c, "Hello, %s!", "world"); // Add "Hello, world!" to output buffer
mg_straddr
char *mg_straddr(struct mg_addr *addr, char *buf, size_t len);
Write stringified IP address, associated with given connection to buf
(maximum size len
)
Parameters:
addr
- A address pointerbuf
- A pointer to a buffer that will hold stringified addresslen
- A buffer size
Return value: buf
value
Usage example:
char buf[100];
LOG(LL_INFO, ("%s", mg_straddr(&c->peer, buf, sizeof(buf))));
mg_wrapfd()
struct mg_connection *mg_wrapfd(struct mg_mgr *mgr, int fd,
mg_event_handler_t fn, void *fn_data);
Wrap a given file descriptor fd
into a connection, and add that connection
to the event manager. An fd
descriptor must support send()
, recv()
,
select()
syscalls, and be non-blocking. Mongoose will treat it as a TCP
socket. The c->rem
and c->loc
addresses will be empty.
Parameters:
fd
- A file descriptor to wrapmgr
- An event managerfn
- A pointer to event handler functionud
- A user data pointer. It will be passed tofn
asfn_data
parameter
Return value: Pointer to the created connection or NULL
in case of error
mg_mkpipe()
int mg_mkpipe(struct mg_mgr *mgr, mg_event_handler_t fn, void *fn_data, bool udp);
Create two interconnected sockets for inter-thread communication. One socket
is wrapped into a Mongoose connection and is added to the event manager.
Another socket is returned, and supposed to be passed to a worker thread.
When a worker thread send()
s to socket any data, that wakes up mgr
and
fn
event handler reveives MG_EV_READ
event. Also, fn
can send any
data to a worker thread, which can be recv()
ed by a worker thread.
If a socketpair is UDP, then it is guaranteed to send a
Parameters:
mgr
- an event managerfn
- a pointer to event handler functionfn_data
- a user data pointer. It will be passed tofn
asfn_data
parameterudp
- tells to create UDP or TCP socketpair.
Return value: created socket, or -1
on error
Usage example: see examples/multi-threaded.
mg_mgr_wakeup()
bool mg_mgr_wakeup(struct mg_connection *pipe, const void *buf, size_len len);
Wake up an event manager that sleeps in mg_mgr_poll()
call. This function
must be called from a separate task/thread. A calling thread can pass
some specific data to the IO thread via buf
, len
. The maximum value
of len
is limited by a maximum UDP datagram size, which is 64KiB. If you need
to send a large data to the Mongoose thread, malloc()
the data and send
a pointer to it, not the data itself. The receiving event handler can receive
a pointer, send a response, and call free()
. Parameters:
Parameters:
pipe
- a special connection created by themg_mkpipe()
callbuf
- a data to send to the pipe connection. Use""
if there is no datalen
- a data length
Return value: true
if data has been sent, false
otherwise
Usage example: see examples/multi-threaded.
HTTP
struct mg_http_header
struct mg_http_header {
struct mg_str name; // Header name
struct mg_str value; // Header value
};
Structure represents HTTP header, like Content-Type: text/html
.
Content-Type
is a header name and text/html
is a header value.
struct mg_http_message
struct mg_http_message {
struct mg_str method, uri, query, proto; // Request/response line
struct mg_http_header headers[MG_MAX_HTTP_HEADERS]; // Headers
struct mg_str body; // Body
struct mg_str message; // Request line + headers + body
};
Structure represents the HTTP message.
mg_http_listen()
struct mg_connection *mg_http_listen(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fn_data);
Create HTTP listener.
Parameters:
mgr
- An event managerurl
- A URL, specifies local IP address and port to listen on, e.g.http://0.0.0.0:8000
fn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: Pointer to created connection or NULL
in case of error
Usage example:
struct mg_connection *c = mg_http_listen(&mgr, "0.0.0.0:8000", fn, arg);
if (c == NULL) fatal_error("Cannot create listener");
mg_http_connect()
struct mg_connection *mg_http_connect(struct mg_mgr *, const char *url,
mg_event_handler_t fn, void *fn_data);
Create HTTP client connection.
Note: This function does not connect to peer; it allocates required resources and
starts connect process. Once peer is really connected MG_EV_CONNECT
event is
sent to connection event handler.
Parameters:
mgr
- An event managerurl
- A URL, specifies remote URL, e.g.http://google.com
fn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: Pointer to created connection or NULL
in case of error
Usage example:
struct mg_connection *c = mg_http_connect(&mgr, "http://google.com", fn, NULL);
if (c == NULL) fatal_error("Cannot create connection");
mg_http_status()
int mg_http_status(const struct mg_http_message *hm);
Get status code of the HTTP response. Parameters:
hm
- Parsed HTTP response
Return value: status code, e.g. 200
for success.
mg_http_get_request_len()
int mg_http_get_request_len(const unsigned char *buf, size_t buf_len);
Get length of request.
The length of request is a number of bytes till the end of HTTP headers. It does not include length of HTTP body.
Parameters:
buf
- A pointer to a buffer with requestbuf_len
- Buffer length
Return value: -1 on error, 0 if a message is incomplete, or the length of request
Usage example:
const char *buf = "GET /test \n\nGET /foo\n\n";
int req_len = mg_http_get_request_len(buf, strlen(buf)); // req_len == 12
mg_http_parse()
int mg_http_parse(const char *s, size_t len, struct mg_http_message *hm);
Parse string request into mg_http_message
structure
Parameters:
s
- A request stringlen
- A request string lengthhm
- A pointer to a structure to store parsed request
Return value: request length (see mg_http_get_request_len()
)
Usage example:
struct mg_http_message hm;
const char *buf = "GET / HTTP/1.0\n\n";
if (mg_http_parse(buf, strlen(buf), &hm) > 0) { /* success */ }
mg_http_printf_chunk()
void mg_http_printf_chunk(struct mg_connection *c, const char *fmt, ...);
Write a chunk of data in chunked encoding format, using printf()
semantic.
Parameters:
c
- A connection pointerfmt
- A string, format specified inprintf
semantics
Return value: None
Usage example:
mg_http_printf_chunk(c, "Hello, %s!", "world");
mg_http_write_chunk()
void mg_http_write_chunk(struct mg_connection *c, const char *buf, size_t len);
Write a chunk of data in chunked encoding format.
Parameters:
c
- A connection pointerbuf
- Data to writelen
- Data length
Return value: None
Usage example:
mg_http_write_chunk(c, "hi", 2);
mg_http_delete_chunk()
void mg_http_delete_chunk(struct mg_connection *c, struct mg_http_message *hm);
Remove chunk specified from input buffer.
Parameters:
c
- A connection pointerhm
- Chunk to delete
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_CHUNK) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
mg_http_delete_chunk(c, hm); // Remove received chunk
}
}
struct mg_http_serve_opts
struct mg_http_serve_opts {
const char *root_dir; // Web root directory, must be non-NULL
const char *ssi_pattern; // SSI file name pattern, e.g. #.shtml
const char *extra_headers; // Extra HTTP headers to add in responses
const char *mime_types; // Extra mime types, ext1=type1,ext2=type2,..
const char *page404; // Path to the 404 page, or NULL by default
struct mg_fs *fs; // Filesystem implementation. Use NULL for POSIX
};
A structure passed to mg_http_serve_dir()
and mg_http_serve_file()
, which
drives the behavior of those two functions.
mg_http_serve_dir()
void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
const struct mg_http_serve_opts *opts);
Serve static files according to the given options. Note that in order to
enable SSI, set a -DMG_ENABLE_SSI=1
build flag.
NOTE: Avoid double dots ..
in
the root_dir
. If you need to
reference an upper-level directory, use absolute path.
Parameters:
c
- Connection to usehm
- HTTP message, that should be servedopts
- Serve options. Note thatopts.root_dir
can optionally accept extra comma-separateduri=path
pairs, see example below
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
struct mg_http_serve_opts opts;
memset(&opts, 0, sizeof(opts));
opts.root_dir = "/var/www,/conf=/etc"; // Serve /var/www. URIs starting with /conf are served from /etc
mg_http_serve_dir(c, hm, &opts);
}
}
mg_http_serve_file()
void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
const char *path, struct mg_http_serve_opts *opts);
Serve static file.
NOTE: opts->root_dir
settings
is ignored by this function.
NOTE: opts->extra_headers
must end with \r\n
.
Parameters:
c
- Connection to usehm
- HTTP message to servepath
- Path to file to serveopts
- Serve options
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
struct mg_http_serve_opts opts = {
.mime_types = "png=image/png",
.extra_headers = "AA: bb\r\nCC: dd\r\n"
};
mg_http_serve_file(c, hm, "a.png", &opts);
}
}
mg_http_reply()
void mg_http_reply(struct mg_connection *c, int status_code,
const char *headers, const char *body_fmt, ...);
Send simple HTTP response using printf()
semantic. This function formats
response body according to a body_fmt
, and automatically appends a correct
Content-Length
header. Extra headers could be passed via headers
parameter.
Parameters:
c
- Connection to usestatus_code
- An HTTP response codeheaders
- Extra headers, default NULL. If not NULL, must end with\r\n
fmt
- A format string for the HTTP body, in a printf semantics
Return value: None
Usage examples:
Send a simple JSON response:
mg_http_reply(c, 200, "Content-Type: application/json\r\n", "{\"result\": %d}", 123);
Send JSON response:
char *json = mg_mprintf("{%Q:%d}", "name", 123);
mg_http_reply(c, 200, "Content-Type: application/json\r\n", "%s\n", json);
free(json);
Send a 302 redirect:
mg_http_reply(c, 302, "Location: /\r\n", "");
Send error:
mg_http_reply(c, 403, "", "%s", "Not Authorized\n");
mg_http_get_header()
struct mg_str *mg_http_get_header(struct mg_http_message *hm, const char *name);
Get HTTP header value
Parameters:
hm
- HTTP message to look for headername
- Header name
Return value: HTTP header value or NULL
if not found
Usage example:
// Mongoose event handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
struct mg_str *s = mg_http_get_header(hm, "X-Extra-Header");
if (s != NULL) {
mg_http_reply(c, 200, "", "Holly molly! Header value: %.*s", (int) s->len, s->ptr);
} else {
mg_http_reply(c, 200, "", "Oh no, header is not set...");
}
}
}
mg_http_get_header_var()
struct mg_str mg_http_get_header_var(struct mg_str s, struct mg_str v);
Parse HTTP header (e.g. Cookie header) which has form
name1=value1; name2=value2; ...
and fetch a given variable.
Parameters:
s
- HTTP headername
- variable name name
Return value: a requested variable, or an empty string.
Usage example:
struct mg_str *cookie = mg_http_get_header(hm, "Cookie");
struct mg_str token = mg_str("");
if (cookie != NULL) {
token = mg_http_get_header_var(*cookie, mg_str("access_token"));
}
mg_http_var()
struct mg_str mg_http_var(struct mg_str buf, struct mg_str name);
Fetch an undecoded HTTP variable. Parameters:
buf
- a url-encoded string: HTTP request body or query stringname
- a variable name to fetch
Return value: variable's value. If not found, it it a NULL string.
// We have received a request to /my/uri?a=b&c=d%20
// The hm->query points to "a=b&c=d%20"
struct mg_str v = mg_http_var(hm->query, mg_str("c")); // v = "d%20"
mg_http_get_var()
int mg_http_get_var(const struct mg_str *var, const char *name, char *buf, int len);
Fetch and decode an HTTP variable
Parameters:
var
- HTTP request bodyname
- Variable namebuf
- Buffer to write decoded variablelen
- Buffer size
Return value: Length of decoded variable. A zero or negative value means error
Usage example:
char buf[100] = "";
mg_http_get_var(&hm->body, "key1", buf, sizeof(buf)) {
...
}
mg_http_creds()
void mg_http_creds(struct mg_http_message *hm, char *user, size_t userlen,
char *pass, size_t passlen);
Fetch authentication credential from the request, and store into the
user
, userlen
and pass
, passlen
buffers. The credentials are looked
up in the following order:
- from the
Authorization
HTTP header,- Basic auth fills both user and pass
- Bearer auth fills only pass
- from the
access_token
cookie, fills pass - from the
?access_token=...
query string parameter, fills pass
If none is found, then both user and pass are set to empty nul-terminated strings.
Parameters:
hm
- HTTP message to look for credentialsuser
- buffer to receive user nameuserlen
- size ofuser
bufferpass
- buffer to receive passwordpasslen
- size ofpass
buffer
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
char user[100], pass[100];
mg_http_creds(hm, user, sizeof(user), pass, sizeof(pass)); // "user" is now user name and "pass" is now password from request
}
}
mg_http_match_uri()
bool mg_http_match_uri(const struct mg_http_message *hm, const char *glob);
Check if HTTP request matches a given glob pattern.
Parameters:
hm
- HTTP message to matchglob
- Pattern
Return value: True if HTTP request matches a given glob pattern; false otherwise
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
if (mg_http_match_uri(hm, "/secret")) {
mg_http_reply(c, 200, NULL, "Very big secret!");
} else {
mg_http_reply(c, 200, NULL, "hello world..");
}
}
}
mg_http_bauth()
void mg_http_bauth(struct mg_connection *c, const char *user, const char *pass);
Write a Basic Authorization
header to the output buffer.
Parameters:
c
- Connection to useuser
- User namepass
- Password
Return value: None
Usage example which uses Basic auth to create Stripe subscription:
mg_printf(c, "POST /v1/subscriptions HTTP/1.1\r\n"
"Host: api.stripe.com\r\n"
"Transfer-Encoding: chunked\r\n");
mg_http_bauth(c, stripe_private_key, NULL); // Add Basic auth header
mg_printf(c, "%s", "\r\n"); // End HTTP headers
mg_http_printf_chunk(c, "&customer=%s", customer_id); // Set customer
mg_http_printf_chunk(c, "&items[0][price]=%s", price); // And price
mg_http_printf_chunk(c, ""); // End request
struct mg_http_part
// Parameter for mg_http_next_multipart
struct mg_http_part {
struct mg_str name; // Form field name
struct mg_str filename; // Filename for file uploads
struct mg_str body; // Part contents
};
Structure that describes a single part of a HTTP multipart message.
mg_http_next_multipart()
size_t mg_http_next_multipart(struct mg_str body, size_t offset, struct mg_http_part *part);
Parse the multipart chunk in the body
at a given offset
. An initial
offset
should be 0. Fill up parameters in the provided part
, which could be
NULL. Return offset to the next chunk, or 0 if there are no more chunks.
Parameters:
body
- Message bodyoffset
- Start offsetpart
- Pointer tostruct mg_http_part
to fill
Return value: offset to the next chunk, or 0 if there are no more chunks.
Usage example (or see form upload tutorial ):
struct mg_http_part part;
size_t pos = 0;
while ((pos = mg_http_next_multipart(body, pos, &part)) != 0) {
// Use part
}
A diagram below shows how mg_http_next_multipart()
in action:
mg_http_upload()
int mg_http_upload(struct mg_connection *c, struct mg_http_message *hm,
struct mg_fs *fs, const char *path, size_t max_size);
This is a helper utility function that is used to upload large files by small chunks.
Append HTTP POST data to a file in a specified directory. A file name and
file offset are specified by the query string parameters:
POST /upload?name=firmware.bin&offset=2048 HTTP/1.1
. If the offset is 0, then the
file is truncated. It is a client's responsibility to divide a file into a
smaller chunks and send a sequence of POST requests that will be handled by
this function.
Parameters:
c
- a connectionhm
- a parsed HTTP messagefs
- a filesystem where to write a file, e.g.&mg_fs_posix
path
- a filenamemax_size
- a maximum allowed file size
Return value: file size after write, or negative number on error
Usage example:
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
if (mg_http_match_uri(hm, "/upload")) {
mg_http_upload(c, hm, &mg_fs_posix, "/tmp/myfile.bin", 99999);
} else {
struct mg_http_serve_opts opts = {.root_dir = "."}; // Serve
mg_http_serve_dir(c, ev_data, &opts); // static content
}
}
}
Websocket
struct mg_ws_message
struct mg_ws_message {
struct mg_str data; // Websocket message data
uint8_t flags; // Websocket message flags
};
Structure represents the WebSocket message.
mg_ws_connect()
struct mg_connection *mg_ws_connect(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fn_data,
const char *fmt, ...);
Create client Websocket connection.
Note: this function does not connect to peer, it allocates required resources and
starts the connect process. Once peer is really connected, the MG_EV_CONNECT
event is
sent to connection event handler.
Parameters:
mgr
- Event manager to useurl
- Specifies remote URL, e.g.http://google.com
opts
- MQTT options, with client ID, QoS, etcfn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
fmt
- printf-like format string for additional HTTP headers, or NULL
Return value: Pointer to created connection or NULL
on error
Usage example:
struct mg_connection *c = mg_ws_connect(&mgr, "ws://test_ws_server.com:1000",
handler, NULL, "%s", "Sec-WebSocket-Protocol: echo\r\n");
if(c == NULL) fatal("Cannot create connection");
mg_ws_upgrade()
void mg_ws_upgrade(struct mg_connection *c, struct mg_http_message *,
const char *fmt, ...);
Upgrade given HTTP connection to Websocket. The fmt
is a printf-like
format string for the extra HTTP headers returned to the client in a
Websocket handshake. Set fmt
to NULL
if no extra headers need to be passed.
Parameters:
c
- Connection to usehm
- HTTP messagefmt
- printf-like format string for additional HTTP headers, or NULL
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
mg_ws_upgrade(c, hm, NULL); // Upgrade HTTP to WS
}
}
mg_ws_send()
size_t mg_ws_send(struct mg_connection *c, const void *buf, size_t len, int op);
Send data to websocket peer
Parameters:
c
- Connection to usebuf
- Data to sendlen
- Data sizeop
- Websocket message type
Return value: sent bytes count
Possible Websocket message type:
#define WEBSOCKET_OP_CONTINUE 0
#define WEBSOCKET_OP_TEXT 1
#define WEBSOCKET_OP_BINARY 2
#define WEBSOCKET_OP_CLOSE 8
#define WEBSOCKET_OP_PING 9
#define WEBSOCKET_OP_PONG 10
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_WS_OPEN) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
mg_ws_send(c, "opened", 6, WEBSOCKET_OP_BINARY); // Send "opened" to web socket connection
}
}
mg_ws_printf(), mg_ws_vprintf()
size_t mg_ws_printf(struct mg_connection *, int op, const char *fmt, ...);
size_t mg_ws_vprintf(struct mg_connection *, int op, const char *fmt, va_list *);
Same as mg_ws_send()
, but formats data using printf()
semantics.
NOTE: See mg_ws_send for the list of possible Websocket message types
NOTE: See mg_snprintf for the list of supported format specifiers
Parameters:
c
- Connection to useop
- Websocket message typefmt
- format string inprintf
semantics
Return value: sent bytes count
Usage example:
mg_ws_printf(c, WEBSOCKET_OP_TEXT, "Hello, %s!", "world");
mg_ws_wrap()
size_t mg_ws_wrap(struct mg_connection *c, size_t len, int op)
Convert data in output buffer to WebSocket format. Useful then implementing protocol over WebSocket See examples/mqtt-over-ws-client for full example.
Parameters:
c
- Connection to uselen
- Bytes count to convertop
- Websocket message type (seemg_ws_send
)
Return value: New size of connection output buffer
Usage example:
size_t len = c->send.len; // Store output buffer len
mg_mqtt_login(c, s_url, &opts); // Write MQTT login message
mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY); // Wrap it into WS
SNTP
mg_sntp_connect()
struct mg_connection *mg_sntp_connect(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fn_data)
Connect SNTP server.
Parameters:
mgr
- Event manager to useurl
- Specifies remote URL,time.google.com
if NULL.fn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: Pointer to created connection or NULL
on error
Usage example:
static void sntp_cb(struct mg_connection *c, int ev, void *evd, void *fnd) {
if (ev == MG_EV_SNTP_TIME) {
// Time received
struct timeval *tv = (struct timeval *tv)evd;
}
}
...
mg_sntp_connect(mgr&, NULL /* connect to time.google.com */, sntp_cb, NULL);
mg_sntp_request()
void mg_sntp_request(struct mg_connection *c)
Send time request to SNTP server
Parameters:
c
- Connection to use
Return value: None
Usage example:
mg_sntp_request(c);
MQTT
struct mg_mqtt_opts
struct mg_mqtt_opts {
struct mg_str user; // Username, can be empty
struct mg_str pass; // Password, can be empty
struct mg_str client_id; // Client ID
struct mg_str will_topic; // Will topic
struct mg_str will_message; // Will message
uint8_t will_qos; // Will message quality of service
uint8_t version; // Can be 4 (3.1.1), or 5. If 0, assume 4.
uint16_t keepalive; // Keep-alive timer in seconds
bool will_retain; // Retain last will
bool clean; // Use clean session, 0 or 1
};
Structure used to specify MQTT connection options.
struct mg_mqtt_message
struct mg_mqtt_message {
struct mg_str topic; // Parsed topic
struct mg_str data; // Parsed message
struct mg_str dgram; // Whole MQTT datagram, including headers
uint16_t id; // Set for PUBACK, PUBREC, PUBREL, PUBCOMP, SUBACK, PUBLISH
uint8_t cmd; // MQTT command, one of MQTT_CMD_*
uint8_t qos; // Quality of service
uint8_t ack; // Connack return code. 0 - success
};
Structure represents the MQTT message.
mg_mqtt_connect()
struct mg_connection *mg_mqtt_connect(struct mg_mgr *mgr, const char *url,
struct mg_mqtt_opts *opts,
mg_event_handler_t fn, void *fn_data);
Create client MQTT connection.
Note: This function does not connect to peer; it allocates required resources and
starts connect process. Once peer is really connected MG_EV_CONNECT
event is
sent to connection event handler.
Parameters:
mgr
- Event manager to useurl
- Specifies remote URL, e.g.http://google.com
opts
- MQTT options, with client ID, qos, etcfn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: pointer to created connection or NULL
on error
Usage example:
void fn(struct mg_connection *c, int ev, void *evd, void *fnd) {
char *buf = (char *) fnd;
if (ev == MG_EV_MQTT_OPEN) {
// Connection ready
}
}
mg_mqtt_connect(&mgr, "mqtt://test.org:1883", NULL, handler, NULL);
mg_mqtt_listen()
struct mg_connection *mg_mqtt_listen(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fn_data);
Create MQTT listener.
Parameters:
mgr
- Event manager to useurl
- Specifies local IP address and port to listen on, e.g.mqtt://0.0.0.0:1883
fn
- An event handler functionfn_data
- An arbitrary pointer, which will be passed asfn_data
when an event handler is called. This pointer is also stored in a connection structure asc->fn_data
Return value: Pointer to created connection or NULL
on error
Usage example:
struct mg_connection *c = mg_mqtt_listen(&mgr, "0.0.0.0:1883", fn, arg);
if (c == NULL) fatal("Cannot create connection");
mg_mqtt_login
void mg_mqtt_login(struct mg_connection *c, const char *url,
struct mg_mqtt_opts *opts);
Send MQTT login request.
Parameters:
c
- Connection to useurl
- URL, containing user name and password to useopts
- Request options
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *evd, void *fnd) {
char *buf = (char *) fnd;
if (ev == MG_EV_MQTT_OPEN) {
struct mg_mqtt_opts opts = {.qos = 1,
.will_topic = mg_str("my topic"),
.will_message = mg_str("goodbye")};
mg_mqtt_login(c, s_url, &opts);
}
}
mg_mqtt_pub()
void mg_mqtt_pub(struct mg_connection *c, struct mg_str topic,
struct mg_str data, int qos, bool retain);
Publish message.
Parameters:
c
- Connection to usetopic
- Topic to publish datadata
- Data to publishqos
- Required QoSretain
- Retain flag
Return value: None
Usage example:
mg_mqtt_pub(c, mg_str("topic"), mg_str("my data"), 1, false);
mg_mqtt_sub()
void mg_mqtt_sub(struct mg_connection *c, struct mg_str topic, int qos);
Subscribe to topic.
Parameters:
c
- Connection to usetopic
- Topic to subscribeqos
- Required QoS
Return value: None
mg_mqtt_sub(c, mg_str("my/topic"), 1);
mg_mqtt_send_header()
void mg_mqtt_send_header(struct mg_connection *c, uint8_t cmd, uint8_t flags, uint32_t len);
Send MQTT command header. Useful in MQTT server implementation. Command can be one of the following value:
#define MQTT_CMD_CONNECT 1
#define MQTT_CMD_CONNACK 2
#define MQTT_CMD_PUBLISH 3
#define MQTT_CMD_PUBACK 4
#define MQTT_CMD_PUBREC 5
#define MQTT_CMD_PUBREL 6
#define MQTT_CMD_PUBCOMP 7
#define MQTT_CMD_SUBSCRIBE 8
#define MQTT_CMD_SUBACK 9
#define MQTT_CMD_UNSUBSCRIBE 10
#define MQTT_CMD_UNSUBACK 11
#define MQTT_CMD_PINGREQ 12
#define MQTT_CMD_PINGRESP 13
#define MQTT_CMD_DISCONNECT 14
Parameters:
c
- Connection to usecmd
- Command (see above)flags
- Command flagslen
- Size of the following command
Return value: None
Usage example:
// Mongoose events handler
void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_MQTT_CMD) {
struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
if (mm->cmd == MQTT_CMD_CONNECT) {
uint8_t response[] = {0, 0};
mg_mqtt_send_header(c, MQTT_CMD_CONNACK, 0, sizeof(response)); // Send acknowledgement
mg_send(c, response, sizeof(response));
}
}
}
mg_mqtt_ping()
void mg_mqtt_ping(struct mg_connection *c);
Send MQTT_CMD_PINGREQ
command via mg_mqtt_send_header
Parameters:
c
- Connection to use
Return value: None
Usage example:
// Send periodic pings to all WS connections
static void timer_fn(void *arg) {
struct mg_mgr *mgr = (struct mg_mgr *) arg;
for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
if (c->is_websocket) mg_mqtt_ping(c);
}
}
mg_mqtt_parse
int mg_mqtt_parse(const uint8_t *buf, size_t len, struct mg_mqtt_message *m);
Parse buffer and fill mg_mqtt_message
structure if buffer contain MQTT message.
Parameters:
buf
- buffer with MQTT message to parselen
- buffer sizem
- pointer tomg_mqtt_message
structure to receive parsed message
Return value: MQTT_OK
if message successfully parsed, MQTT_INCOMPLETE
if message
isn't fully received and MQTT_MALFORMED
if message has wrong format.
Usage example:
// Iterate over all MQTT frames contained in buf, len
struct mg_mqtt_message mm;
while ((mg_mqtt_parse(buf, len, &mm)) == MQTT_OK) {
switch (mm.cmd) {
case MQTT_CMD_CONNACK:
...
}
buf += mm.dgram.len;
len -= mm.dgram.len;
}
TLS
struct mg_tls_opts
struct mg_tls_opts {
const char *ca; // CA certificate file. For both listeners and clients
const char *crl; // Certificate Revocation List. For clients
const char *cert; // Certificate
const char *certkey; // Certificate key
const char *ciphers; // Cipher list
struct mg_str srvname; // If not empty, enables server name verification
struct mg_fs *fs; // FS API for reading certificate files
};
TLS initialisation structure:
ca
- Certificate Authority. Can be a filename or a string. Used to verify a certificate that the other end sends to us. If NULL, then certificate checking is disabledcrl
- Certificate Revocation List. Can be a filename or a string. Used to verify a certificate that the other end sends to us. If NULL, then certificate revocation checking is disabledcert
- Our own certificate. Can be a filename, or a string. If NULL, then we don't authenticate with the other peercertkey
- A key for acert
. Sometimes, a certificate and its key are bundled in a single .pem file, in which case the values forcert
andcertkey
could be the sameciphers
- A list of allowed cipherssrvname
- Enable server name verification
NOTE: if both ca
and cert
are set, then so-called two-way TLS is enabled,
when both sides authenticate with each other. Usually, server-side connections
set both ca
and cert
, whilst client-side - only ca
.
mg_tls_init()
void mg_tls_init(struct mg_connection *c, struct mg_tls_opts *opts);
Initialise TLS on a given connection.
NOTE: mbedTLS implementation uses mg_random
as RNG. The mg_random
can be overridden by setting MG_ENABLE_CUSTOM_RANDOM
and defining your own mg_random()
implementation.
Parameters:
c
- Connection, for which TLS should be initializedopts
- TLS initialization parameters
Return value: None
Usage example:
struct mg_tls_opts opts = {.cert = "ca.pem"};
mg_tls_init(c, &opts);
Timer
mg_timer_add()
struct mg_timer *mg_timer_add(struct mg_mgr *mgr,
uint64_t period_ms, unsigned flags,
void (*fn)(void *), void *fn_data);
Setup a timer. This is a high-level timer API that allows to add a software
timer to the event manager. This function calloc()
s a new timer and
adds it to the mgr->timers
list. All added timers are polled when
mg_mgr_poll()
is called, and called if expired.
NOTE: Make sure that the timer
interval is equal or more to the mg_mgr_poll()
timeout.
Parameters:
mgr
- Pointer tomg_mgr
event manager structurems
- An interval in millisecondsflags
- Timer flags bitmask,MG_TIMER_REPEAT
andMG_TIMER_RUN_NOW
fn
- Function to invokefn_data
- Function argument
Return value: Pointer to created timer
Usage example:
void timer_fn(void *data) {
// ...
}
mg_timer_add(mgr, 1000, MG_TIMER_REPEAT, timer_fn, NULL);
struct mg_timer
struct mg_timer {
uint64_t period_ms; // Timer period in milliseconds
uint64_t expire; // Expiration timestamp in milliseconds
unsigned flags; // Possible flags values below
#define MG_TIMER_ONCE 0 // Call function once
#define MG_TIMER_REPEAT 1 // Call function periodically
#define MG_TIMER_RUN_NOW 2 // Call immediately when timer is set
void (*fn)(void *); // Function to call
void *arg; // Function argument
struct mg_timer *next; // Linkage
};
Timer structure. Describes a software timer. Timer granularity is the same
as the mg_mgr_poll()
timeout argument in the main event loop.
mg_timer_init()
void mg_timer_init(struct mg_timer **head,
struct mg_timer *t, uint64_t period_ms, unsigned flags,
void (*fn)(void *), void *fn_data);
Setup a timer.
Parameters:
head
- Pointer tomg_timer
list headt
- Pointer tomg_timer
that should be initializedms
- An interval in millisecondsflags
- Timer flags bitmask,MG_TIMER_REPEAT
andMG_TIMER_RUN_NOW
fn
- Function to invokefn_data
- Function argument
Return value: None
Usage example:
void timer_fn(void *data) {
// ...
}
struct mg_timer timer, *head = NULL;
mg_timer_init(&head, &timer, 1000, MG_TIMER_REPEAT, timer_fn, NULL);
mg_timer_free()
void mg_timer_free(struct mg_timer **head, struct mg_timer *t);
Free timer, remove it from the internal timers list.
Parameters:
head
- Pointer tomg_timer
list headt
- Timer to free
Return value: None
Usage example:
struct mg_timer timer;
// ...
mg_timer_free(&timer);
mg_timer_poll()
void mg_timer_poll(struct mg_timer **head, uint64_t uptime_ms);
Traverse list of timers and call them if current timestamp uptime_ms
is
past the timer's expiration time.
Note, that mg_mgr_poll
function internally calls mg_timer_poll
; therefore,
in most cases it is unnecessary to call it explicitly.
Parameters:
head
- Pointer tomg_timer
list headuptime_ms
- current timestamp
Return value: None
Usage example:
mg_timer_poll(mg_millis());
Time
mg_millis()
int64_t mg_millis(void);
Return current uptime in milliseconds.
Parameters: None
Return value: Current uptime
Usage example:
int64_t uptime = mg_millis();
String
struct mg_str
struct mg_str {
const char *ptr; // Pointer to string data
size_t len; // String len
};
This structure represent an arbitrary chunk of memory, not necessarily zero-terminated. This is a "mongoose string", and it gets used extensively in the codebase instead of C zero-terminated strings.
For example, when an HTTP request is received, Mongoose created a
struct mg_http_message
which has a collection of struct mg_str
pointing
to request method, URI, headers, and so on. This way, Mongoose avoids
any heap allocations and does not modify the received buffer - instead, it
uses struct mg_str
to describe various parts of HTTP request.
Same goes with many other cases.
NOTE: since ptr
is not necessarily zero-terminated, do not use libc string
functions against it - like strlen()
or sscanf()
.
mg_str()
struct mg_str mg_str(const char *s)
Create Mongoose string from NULL-terminated C-string. This function doesn't
duplicate provided string, and stores pointer within created mg_str
structure.
Note, that is you have problems in C++ (constructor shadowing), there is mg_str_s
synonym for this function.
Parameters:
s
- Pointer to NULL-terminated string to store in created mg_str
Return value: Created Mongoose string
Usage example:
struct mg_str str = mg_str("Hello, world!);
mg_str_n()
struct mg_str mg_str_n(const char *s, size_t n);
Create Mongoose string from C-string s
(can be non-NULL terminated, length is
specified in n
). Note: This function doesn't duplicate provided string,
but stores pointer within created mg_str
structure.
Parameters:
s
- Pointer to string to store in createdmg_str
n
- String length
Return value: Created Mongoose string
Usage example:
struct mg_str str = mg_str_n("hi", 2);
mg_casecmp()
int mg_casecmp(const char *s1, const char *s2);
Case insensitive compare two NULL-terminated strings.
Parameters:
s1
,s2
- Pointers to strings to compare
Return value: Zero if strings are equal, more than zero if first argument is greater then second, and less than zero otherwise
Usage example:
if (mg_casecmp("hello", "HELLO") == 0) {
// Strings are equal
}
mg_ncasecmp()
int mg_ncasecmp(const char *s1, const char *s2, size_t len);
Case insensitive compare two C-strings, not more than len
symbols or until meet \0
symbol.
Parameters:
s1
,s2
- Pointers to strings to comparelen
- Maximum length to compare
Return value: Zero if strings are equal, more than zero if first argument is greater then second, and less than zero otherwise
Usage example:
if (mg_ncasecmp("hello1", "HELLO2", 5) == 0) {
// Strings are equal
}
mg_vcmp()
int mg_vcmp(const struct mg_str *s1, const char *s2);
Compare mongoose string and C-string.
Parameters:
s1
- Pointer to Mongoose string to compares2
- Pointer to C-string to compare
Return value: 0 if strings are equal, more than zero if first argument is greater then second, and less than zero otherwise
Usage example:
struct mg_str str = mg_str("hello");
if (mg_vcmp(str, "hello") == 0) {
// Strings are equal
}
mg_vcasecmp()
int mg_vcasecmp(const struct mg_str *str1, const char *str2);
Case insensitive compare mongoose string and C-string.
Parameters:
str1
- Mongoose string to comparestr2
- C-string to compare
Return value: Zero if strings are equal, more than zero if first argument is greater then second, and less than zero otherwise
Usage example:
struct mg_str str = mg_str("hello");
if (mg_vcasecmp(str, "HELLO") == 0) {
// Strings are equal
}
mg_strcmp()
int mg_strcmp(const struct mg_str str1, const struct mg_str str2);
Compare two mongoose strings.
Parameters:
str1
,str2
- Pointers to Mongoose strings to compare
Return value: Zero if strings are equal, more than zero if first argument is greater then second, and less than zero otherwise
Usage example:
struct mg_str str1 = mg_str("hello");
struct mg_str str2 = mg_str("hello");
if (mg_strcmp(str1, str2) == 0) {
// Strings are equal
}
mg_strdup()
struct mg_str mg_strdup(const struct mg_str s);
Duplicate provided string. Return new string or MG_NULL_STR
on error.
Note: This function allocates memory for returned string. You may need to free it using free
function.
Parameters:
s
- Mongoose string to duplicate
Return value: Duplicated string
Usage example:
struct mg_str str1 = mg_str("hello");
struct mg_str str2 = mg_strdup(str1);
//...
free(str2.ptr);
mg_strstr()
const char *mg_strstr(const struct mg_str haystack, const struct mg_str needle)
Search for needle
substring in haystack
string.
Parameters:
haystack
- Mongoose sting to search for substringneedle
- Mongoose string to search
Return value: pointer to needle
occurrence within haystack
or NULL
if not found.
Usage example:
struct mg_str str = mg_str("Hello, world");
struct mg_str sub_str = mg_str("world");
if (mg_strstr(str, sub_str) != NULL) {
// Found
}
mg_strstrip()
struct mg_str mg_strstrip(struct mg_str s)
Remove heading and trailing whitespace from mongoose string s
.
Parameters:
s
- Mongoose string for trimming
Return value: Input string
Usage example:
struct mg_str str = mg_strstrip(mg_str(" Hello, world "));
if (mg_vcmp(str, "Hello, world") == 0) {
// Strings are equal
}
mg_match()
bool mg_match(struct mg_str str, struct mg_str pattern, struct mg_str *caps);
Check if string str
matches glob pattern pattern
, and optionally capture
wildcards into the provided array caps
.
NOTE: If caps
is not NULL, then the
caps
array size must be at least the number of wildcard symbols in pattern
plus 1. The last cap will be initialized to an empty string.
The glob pattern matching rules are as follows:
?
matches any single character*
matches zero or more characters except/
#
matches zero or more characters- any other character matches itself
Parameters:
str
- a string to matchpattern
- a pattern to match againstcaps
- an optional array of captures for wildcard symbols?
,*
, '#'
Return value: true
if matches, false
otherwise
Usage example:
// Assume that hm->uri holds /foo/bar. Then we can match the requested URI:
struct mg_str caps[3]; // Two wildcard symbols '*' plus 1
if (mg_match(hm->uri, mg_str("/*/*"), caps)) {
// caps[0] holds `foo`, caps[1] holds `bar`.
}
mg_commalist()
bool mg_commalist(struct mg_str *s, struct mg_str *k, struct mg_str *v);
Parse string s
, which is a comma-separated list of entries. An entry could be
either an arbitrary string, which gets stored in v
, or a KEY=VALUE
which
gets stored in k
and v
respectively.
IMPORTANT: This function modifies s
by pointing to the next entry.
Parameters:
s
- String to search for entryk
- Pointer tomg_str
to receive entry keyv
- Pointer tomg_str
to receive entry value
Return value: true
if entry is found, false
otherwise
Usage example:
struct mg_str k, v, s = mg_str("a=333,b=777");
while (mg_commalist(&s, &k, &v)) // This loop output:
printf("[%.*s] set to [%.*s]\n", // [a] set to [333]
(int) k.len, k.ptr, (int) v.len, v.ptr); // [b] set to [777]
mg_hex()
char *mg_hex(const void *buf, size_t len, char *dst);
Hex-encode binary data buf
, len
into a buffer dst
and nul-terminate it.
The output buffer must be at least 2 x len
+ 1 big.
Parameters:
buf
- Data to hex-encodelen
- Data lengthdst
- Pointer to output buffer
Return value: dst
pointer. The encoded characters are lowercase
Usage example:
char data[] = "\x1\x2\x3";
char buf[sizeof(data)*2];
char *hex = mg_hex(data, sizeof(data) - 1, buf);
LOG(LL_INFO, ("%s", hex)); // Output "010203";
free(hex);
mg_unhex()
void mg_unhex(const char *buf, size_t len, unsigned char *to);
Hex-decode string buf
, len
into a buffer to
. The to
buffer should be
at least lsn
/ 2 big.
Parameters:
buf
- Data to hex-decodelen
- Data lengthto
- Pointer to output buffer
Return value: None
Usage example:
char data[] = "010203";
char *buf[sizeof(data)/2];
char *hex = mg_unhex(data, sizeof(data) - 1, buf); // buf is now [1,2,3]
free(hex);
mg_unhexn()
unsigned long mg_unhexn(const char *s, size_t len);
Parse len
characters of the hex-encoded string s
.
The maximum value of len
is the width of the long
x 2, for example
on 32-bit platforms it is 8.
Parameters:
s
- String to parselen
- String length
Return value: Return parsed value
Usage example:
char data[] = "010203";
char *buf[sizeof(data)/2];
unsigned long val = mg_unhex(data, sizeof(data) - 1); // val is now 123
mg_remove_double_dots()
char *mg_remove_double_dots(char *s);
Modify string s
in place by removing double dots from it. Used to
sanitize file names or URIs received from the network.
Parameters:
s
- String to sanitise
Return value: the s
pointer
Usage example:
char data[] = "../../a.txt";
mg_remove_double_dots(data); // data is /a.txt
mg_snprintf(), mg_vsnprintf()
size_t mg_snprintf(char *buf, size_t len, const char *fmt, ...);
size_t mg_vsnprintf(char *buf, size_t len, const char *fmt, va_list ap);
Print formatted string into a string buffer, just like snprintf()
standard function does, but in a predictable way that does not depend on
the C library or the build environment. The return value can be larger
than the buffer length len
, in which case the overflow bytes are not printed.
Mongoose library is often used to exchange data in JSON format, therefore a
non-standard %Q
, %V
, %H
specifiers for formatting JSON strings is also supported.
Parameters:
buf
- Pointer to pointer to output bufferlen
- Buffer sizefmt
- printf-like format string
Supported format specifiers:
hhd
,hd
,d
,ld
,lld
- forchar
,short
,int
,long
,int64_t
hhu
,hu
,u
,lu
,llu
- same but for unsigned variantshhx
,hx
,x
,lx
,llx
- same, unsigned and hex outputs
- expectchar *
q
- expectchar *
, outputs JSON-escaped string (extension)Q
- expectchar *
, outputs double-quoted JSON-escaped string (extension)H
- expectint
,void *
, outputs double-quoted hex string (extension)V
- expectint
,void *
, outputs double-quoted base64 string (extension)M
- expectmg_pfn_t
, calls another print function (extension)g
,f
- expectdouble
c
- expectchar
%
- expect%
character itselfp
- expect any pointer, prints0x.....
hex value%X.Y
- optional width and precision modifiers%.*
- optional precision modifier specified asint
argument
Return value: Number of bytes printed
Sending JSON HTTP response:
mg_http_reply(c, 200, "Content-Type: application/json\r\n",
"{%Q: %g}", "value", 1.2345);
Example of using more complex format strings:
mg_snprintf(buf, sizeof(buf), "%lld", (int64_t) 123); // 123
mg_snprintf(buf, sizeof(buf), "%.2s", "abcdef"); // ab
mg_snprintf(buf, sizeof(buf), "%.*s", 2, "abcdef"); // ab
mg_snprintf(buf, sizeof(buf), "%05x", 123); // 00123
mg_snprintf(buf, sizeof(buf), "%%-%3s", "a"); // %- a
mg_snprintf(buf, sizeof(buf), "hi, %Q", "a"); // hi, "a"
mg_snprintf(buf, sizeof(buf), "r: %M, %d", f,1,2,7); // r: 3, 7
// Printing sub-function for %M specifier. Grabs two int parameters
size_t f(void (*out)(char, void *), void *ptr, va_list *ap) {
int a = va_arg(*ap, int);
int b = va_arg(*ap, int);
return mg_xprintf(out, ptr, "%d", a + b);
}
mg_mprintf(), mg_vmprintf()
char *mg_mprintf(const char *fmt, ...);
char *mg_vmprintf(const char *fmt, va_list *ap);
Print message into an allocated memory buffer. Caller must free the result.
Parameters:
fmt
- printf-like format string
Return value: allocated memory buffer
Usage example:
char *msg = mg_mprintf("Double quoted string: %Q!", "hi");
free(msg);
mg_xprintf(), mg_vxprintf()
size_t mg_xprintf(void (*out)(char, void *), void *param, const char *fmt, ...);
size_t mg_vxprintf(void (*out)(char, void *), void *param, const char *fmt,
va_list *ap);
Print message using a specified character output function
Parameters:
out
- function to be used for printing charsparam
- argument to be passed toout
fmt
- printf-like format string
Return value: Number of bytes printed
Usage example:
void myfn(char c, void *p);
size_t len = mg_xprintf(myfn, myfn_p, "Double quoted string: %Q!", "hi");
mg_pfn_iobuf()
void mg_pfn_iobuf(char ch, void *param);
Print a character to a Generic IO buffer
Parameters:
ch
- char to be printedparam
- must bestruct mg_iobuf *
Usage example:
mg_xprintf(mg_pfn_iobuf, &c->send, "hi!"); // Append to the output buffer
mg_to64()
int64_t mg_to64(struct mg_str str);
uint64_t mg_tou64(struct mg_str str);
Parse 64-bit integer value held by string s
.
Parameters:
str
- String to parse
Return value: Parsed value
Usage example:
int64_t val = mg_to64(mg_str("123")); // Val is now 123
mg_aton()
bool mg_aton(struct mg_str str, struct mg_addr *addr);
Parse IP address held by str
and store it in addr
.
Parameters:
str
- String to parse, for example1.2.3.4
,[::1]
,01:02::03
addr
- Pointer tomg_addr
string to receive parsed value
Return value: true
on success, false
otherwise
Usage example:
struct mg_addr addr;
if (mg_aton(mg_str("127.0.0.1"), &addr)) {
// addr is now binary representation of 127.0.0.1 IP address
}
mg_ntoa()
char *mg_ntoa(const struct mg_addr *addr, char *buf, size_t len);
Stringify IP address ipaddr
into a buffer buf
, len
Parameters:
addr
- Address to stringifybuf
- Pointer to output bufferlen
- Output buffer size
Return value: buf
value
Usage example:
char buf[100];
mg_ntoa(&c->peer, buf, sizeof(buf));
JSON
Note that Mongoose's printing functions support non-standard format specifiers %Q
and %M
,
which allow to print JSON strings easily:
char *json = mg_mprintf("{%Q:%d}", "value", 123); // {"value":123}
free(json);
Therefore, for a full JSON support, a set of parsing functions is required - which is described below.
mg_json_get()
enum { MG_JSON_TOO_DEEP = -1, MG_JSON_INVALID = -2, MG_JSON_NOT_FOUND = -3 };
int mg_json_get(struct mg_str json, const char *path, int *toklen);
Parse JSON string json
and return the offset of the element
specified by the JSON path
. The length of the element is stored
in the toklen
.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
, e.g.$.user
toklen
- a pointer that receives element's length, can be NULL
Return value: offset of the element, or negative MG_JSON_*
on error.
Usage example:
// Create a json string: { "a": 1, "b": [2, 3] }
char *buf = mg_mprintf("{ %Q: %d, %Q: [%d, %d] }", "a", 1, "b", 2, 3);
struct mg_str json = mg_str(buf);
int offset, length;
// Lookup "$", which is the whole JSON. Can be used for validation
offset = mg_json_get(json, "$", &length); // offset = 0, length = 23
// Lookup attribute "a". Point to value "1"
offset = mg_json_get(json, "$.a", &length); // offset = 7, length = 1
// Lookup attribute "b". Point to array [2, 3]
offset = mg_json_get(json, "$.b", &length); // offset = 15, length = 6
// Lookup attribute "b[1]". Point to value "3"
offset = mg_json_get(json, "$.b[1]", &length); // offset = 19, length = 1
free(buf);
mg_json_get_num()
bool mg_json_get_num(struct mg_str json, const char *path, double *v);
Fetch numeric (double) value from the json string json
at JSON path
path
into a placeholder v
. Return true if successful.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
v
- a placeholder for value
Return value: true on success, false on error
Usage example:
double d = 0.0;
mg_json_get_num(mg_str("[1,2,3]", "$[1]", &d)); // d contains 2
mg_json_get_num(mg_str("{\"a\":1.23}", "$.a", &d)); // d contains 1.23
mg_json_get_bool()
bool mg_json_get_bool(struct mg_str json, const char *path, bool *v);
Fetch boolean (bool) value from the json string json
at JSON path
path
into a placeholder v
. Return true if successful.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
v
- a placeholder for value
Return value: true on success, false on error
Usage example:
bool b = false;
mg_json_get_bool(mg_str("[123]", "$[0]", &b)); // Error. b remains to be false
mg_json_get_bool(mg_str("[true]", "$[0]", &b)); // b is true
mg_json_get_long()
long mg_json_get_long(struct mg_str json, const char *path, long default_val);
Fetch integer numeric (long) value from the json string json
at JSON path
path
. Return it if found, or default_val
if not found.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
default_val
- a default value for the failure case
Return value: found value, or default_val
value
Usage example:
long a = mg_json_get_long(mg_str("[123]", "$a", -1)); // a = -1
long b = mg_json_get_long(mg_str("[123]", "$[0]", -1)); // b = 123
mg_json_get_str()
char *mg_json_get_str(struct mg_str json, const char *path);
Fetch string value from the json string json
at JSON path
path
. If found, a string is allocated using calloc()
,
un-escaped, and returned to the caller. It is the caller's responsibility to
free()
the returned string.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
Return value: non-NULL on success, NULL on error
Usage example:
struct mg_str json = mg_str("{\"a\": \"hi\"}"); // json = {"a": "hi"}
char *str = mg_json_get_str(json, "$.a"); // str = "hi"
free(str);
mg_json_get_hex()
char *mg_json_get_hex(struct mg_str json, const char *path, int *len);
Fetch hex-encoded buffer from the json string json
at JSON path
path
. If found, a buffer is allocated using calloc()
, decoded,
and returned to the caller. It is the caller's responsibility to
free()
the returned string. Returned buffer is 0-terminated.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
len
- a pointer that receives decoded length. Can be NULL
Return value: non-NULL on success, NULL on error
Usage example:
struct mg_str json = mg_str("{\"a\": \"6869\"}"); // json = {"a": "6869"}
char *str = mg_json_get_hex(json, "$.a", NULL); // str = "hi"
free(str);
mg_json_get_b64()
char *mg_json_get_b4(struct mg_str json, const char *path, int *len);
Fetch base64-encoded buffer from the json string json
at JSON path
path
. If found, a buffer is allocated using calloc()
, decoded,
and returned to the caller. It is the caller's responsibility to
free()
the returned string. Returned buffer is 0-terminated.
Parameters:
json
- a string containing valid JSONpath
- a JSON path. Must start with$
len
- a pointer that receives decoded length. Can be NULL
Return value: non-NULL on success, NULL on error
Usage example:
struct mg_str json = mg_str("{\"a\": \"YWJj\"}"); // json = {"a": "YWJj"}
char *str = mg_json_get_b64(json, "$.a", NULL); // str = "abc"
free(str);
RPC
Mongoose includes a set of functions to ease server-side processing by means of RPC methods.
struct mg_rpc
The RPC method handler structure. Each method has an entry in a linked list, each entry points to a string describing the pattern that will invoke it and the function that will be called to satisfy the method invocation, with a proper function argument.
struct mg_rpc {
struct mg_rpc *next; // Next in list
struct mg_str method; // Method pattern
void (*fn)(struct mg_rpc_req *); // Handler function
void *fn_data; // Handler function argument
};
struct mg_rpc_req
The RPC request descriptor. An invoked method receives a descriptor containing the request, and a pointer to a function to be called to print the output response, with a proper function argument; e.g.: mg_pfn_realloc() or mg_pfn_iobuf()
struct mg_rpc_req {
struct mg_rpc **head; // RPC handlers list head
struct mg_rpc *rpc; // RPC handler being called
mg_pfn_t pfn; // Response printing function
void *pfn_data; // Response printing function data
void *req_data; // Arbitrary request data
struct mg_str frame; // Request, e.g. {"id":1,"method":"add","params":[1,2]}
};
mg_rpc_add()
void mg_rpc_add(struct mg_rpc **head, struct mg_str method_pattern,
void (*handler)(struct mg_rpc_req *), void *handler_data);
Add the method method_pattern
to the list head
of RPC methods. Invoking this method will call handler
and pass handler_data
to it with the request (as r->fn_data
in the usage example below).
Parameters:
head
- the linked list pointermethod_pattern
- the name of the methodhandler
- the RPC function performing the action for this methodhandler_data
- Arbitrary function data
NOTE:
if method_pattern
is an empty string, this handler will be called to process
JSON-RPC responses. Handling responses might be necessary if the JSON requests
are initiated by both sides.
Usage example:
struct mg_rpc *s_rpc_head = NULL;
static void rpc_sum(struct mg_rpc_req *r) {
double a = 0.0, b = 0.0;
mg_json_get_num(r->frame, "$.params[0]", &a);
mg_json_get_num(r->frame, "$.params[1]", &b);
mg_rpc_ok(r, "%g", a + b);
}
static void rpc_mul(struct mg_rpc_req *r) {//...}
mg_rpc_add(&s_rpc_head, mg_str("sum"), rpc_sum, NULL);
mg_rpc_add(&s_rpc_head, mg_str("mul"), rpc_mul, NULL);
mg_rpc_del()
void mg_rpc_del(struct mg_rpc **head, void (*handler)(struct mg_rpc_req *));
Remove the method with RPC function handler handler
from the list head
of RPC methods.
Parameters:
head
- the linked list pointerhandler
- the RPC function performing the action for this method, use NULL to deallocate all
Usage example:
struct mg_rpc *s_rpc_head = NULL;
// add methods
// ...
// Time to cleanup
mg_rpc_del(&s_rpc_head, rpc_mul); // Deallocate specific handler
mg_rpc_del(&s_rpc_head, NULL); // Deallocate all RPC handlers
mg_rpc_process()
void mg_rpc_process(struct mg_rpc_req *req);
Invoke the proper method for this request. If the requested method does not exist, mg_rpc_err()
will be invoked and an error indication will be printed
Parameters:
req
- a request
Usage example:
struct mg_rpc *s_rpcs = NULL; // Empty RPC list head
mg_rpc_add(&s_rpcs, mg_str("rpc.list"), mg_rpc_list, NULL); // Add rpc.list
// ... add more RPC methods
// On request, process the incoming frame
struct mg_str req = mg_str("{\"id\":1,\"method\":\"sum\",\"params\":[1,2]}");
struct mg_iobuf io = {0, 0, 0, 512}; // Empty IO buf, with 512 realloc granularity
struct mg_rpc_req r = {
.head = &s_rpcs, // RPC list head
.rpc = NULL, // This will be set by mg_rpc_process()
.pfn = mg_pfn_iobuf, // Printing function: print into the io buffer
.pfn_data = &io, // Pass our io buffer as a parameter
.req_data = NULL, // No specific request data
.frame = req, // Specify incoming frame
};
mg_rpc_process(&r);
if (io.buf != NULL) printf("Response: %s\n", (char *) io.buf);
mg_iobuf_free(&io);
mg_rpc_ok(), mg_rpc_vok()
void mg_rpc_ok(struct mg_rpc_req *, const char *fmt, ...);
void mg_rpc_vok(struct mg_rpc_req *, const char *fmt, va_list *ap);
Helper functions to print result frames
Parameters:
req
- a requestfmt
- printf-like format string
Usage example:
static void rpc_sum(struct mg_rpc_req *r) {
double a = 0.0, b = 0.0;
mg_json_get_num(r->frame, "$.params[0]", &a);
mg_json_get_num(r->frame, "$.params[1]", &b);
mg_rpc_ok(r, "%g", a + b);
}
mg_rpc_err(), mg_rpc_verr()
void mg_rpc_err(struct mg_rpc_req *, int code, const char *fmt, ...);
void mg_rpc_verr(struct mg_rpc_req *, int code, const char *fmt, va_list *);
Helper functions to print error frames
Parameters:
req
- a requestfmt
- printf-like format string
Usage example:
static void rpc_dosome(struct mg_rpc_req *r) {
...
mg_rpc_err(r, -32109, "\"%.*s not found\"", len, &r->frame.ptr[offset]);
}
mg_rpc_list()
void mg_rpc_list(struct mg_rpc_req *r);
Built-in RPC method to list all registered RPC methods. This function is not usually called directly, but registered as a method.
Parameters:
req
- a request
Usage example:
mg_rpc_add(&s_rpc_head, mg_str("rpc.list"), mg_rpc_list, &s_rpc_head);
(see also mg_rpc_add())
Utility
mg_call()
void mg_call(struct mg_connection *c, int ev, void *ev_data);
Send ev
event to c
event handler. This function is useful then implementing
your own protocol.
Parameters:
c
- Connection to send eventev
- Event to sendev_data
- Additional event parameter
Return value: None
Usage example:
// In a timer callback, send MG_EV_USER event to all connections
static void timer_fn(void *arg) {
struct mg_mgr *mgr = (struct mg_mgr *) arg;
for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
mg_call(c, MG_EV_USER, "hi!");
}
}
mg_error()
void mg_error(struct mg_connection *c, const char *fmt, ...);
Send MG_EV_ERROR
to connection event handler with error message formatted using printf semantics.
Parameters:
c
- Connection to send eventfmt
- Format string inprintf
semantics
Return value: None
Usage example:
mg_error(c, "Operation failed, error code: %d", errno);
mg_md5_init()
void mg_md5_init(mg_md5_ctx *c);
Initialize context for MD5 hashing.
Parameters:
c
- Pointer tomg_md5_ctx
structure to initialize
Return value: None
Usage example:
mg_md5_ctx ctx;
mg_md5_init(&ctx);
mg_md5_update()
void mg_md5_update(mg_md5_ctx *c, const unsigned char *data, size_t len);
Hash len
bytes of data pointed by data
using MD5 algorithm.
Parameters:
c
- MD5 contextdata
- Data to hashlen
- Data length
Return value: None
Usage example:
mg_md5_ctx ctx;
// Context initialization
// ...
mg_md5_update(&ctx, "data", 4); // hash "data" string
mg_md5_update(&ctx, "more data", 9); // hash "more data" string
mg_md5_final()
void mg_md5_final(mg_md5_ctx *c, unsigned char buf[16]);
Get current MD5 hash for context.
Parameters:
c
- MD5 contextbuf
- Pointer to buffer to write MD5 hash value
Return value: None
Usage example:
mg_md5_ctx ctx;
// Context initialization
// ...
unsigned char buf[16];
mg_md5_final(&ctx, buf); // `buf` is now MD5 hash
mg_sha1_init()
void mg_sha1_init(mg_sha1_ctx *c);
Initialize context for calculating SHA1 hash
Parameters:
c
- pointer tomg_sha1_ctx
structure to initialize
Return value: none
Usage example:
mg_sha1_ctx ctx;
mg_sha1_init(&ctx);
mg_sha1_update()
void mg_sha1_update(mg_sha1_ctx *c, const unsigned char *data, size_t len);
Hash len
bytes of data
using SHA1 algorithm.
Parameters:
c
- SHA1 contextdata
- Data to hashlen
- Data length
Return value: None
Usage example:
mg_sha1_ctx ctx;
// Context initialization
// ...
mg_sha1_update(&ctx, "data", 4); // hash "data" string
mg_sha1_update(&ctx, "more data", 9); // hash "more data" string
mg_sha1_final()
void mg_sha1_final(unsigned char digest[20], mg_sha1_ctx *c);
Get current SHA1 hash for context.
Parameters:
c
- SHA1 contextdigest
- Pointer to buffer to receive hash value
Return value: None
Usage example:
mg_sha1_ctx ctx;
// Context initialization
// ...
unsigned char buf[20];
mg_sha1_final(buf, &ctx); // `buf` is now SHA1 hash
mg_base64_update()
int mg_base64_update(unsigned char p, char *out, int pos);
Encode p
byte to base64 and write result into out
buffer starting with pos
position.
Parameters:
p
- Byte to encodeout
- Pointer to buffer to write resultpos
- Position in output buffer to write result
Return value: New position for further operations
Usage example:
char buf[10];
mg_base64_update((unsigned char)"a", buf, 0); // Encode "a" into base64 and write it to the beginning of buf
mg_base64_final()
int mg_base64_final(char *buf, int pos);
Add base64 finish mark and \0
symbol to buf
at pos
position.
Parameters:
buf
- Pointer to buffer to write finish markpos
- Position to write
Return value: New position for further operations
char buf[10];
int pos;
// ...
mg_base64_final(buf, pos);
mg_base64_encode()
int mg_base64_encode(const unsigned char *p, int n, char *to);
Encode n
bytes data pointed by p
using base64 and write result into to
.
Parameters:
p
- Pointer to data to encoden
- Data lengthto
- Pointer to buffer to write result
Return value: Written symbols number
Usage example:
char buf[128];
mg_base64_encode((uint8_t *) "abcde", 5, buf); // buf is now YWJjZGU=
mg_base64_decode()
int mg_base64_decode(const char *src, int n, char *dst);
Decode n
bytes of base64-ed src
and write it to dst
.
Parameters:
src
- Data to decoden
- Data lengthdst
- Pointer to output buffer
Return value: Number of written symbols.
Usage example:
char buf[128];
mg_base64_decode("Q2VzYW50YQ==", 12, buf); // buf is now "Cesanta"
mg_random()
void mg_random(void *buf, size_t len);
Fill in buffer buf
, len
with random data. Note: Mongoose uses this
function for TLS and some other routines that require RNG (random number
generator). It is possible to override a built-in mg_random()
by specifying
a MG_ENABLE_CUSTOM_RANDOM=1
build preprocessor constant.
Parameters:
buf
- Pointer to buffer to receive random datalen
- Buffer size
Return value: None
Usage example:
char buf[10];
mg_random(buf, sizeof(buf)); // `buf` is now random bytes
mg_random_str()
char *mg_random_str(char *buf, size_t len);
Fill in buffer buf
, len
with random alphanumeric characters: a-zA-Z0-9
.
A buffer is zero-terminated.
Parameters:
buf
- a pointer to a bufferlen
- a buffer size
Return value: buf
value.
Usage example:
char buf[10];
printf("Random: %s\n", mg_random_str(buf, sizeof(buf)));
mg_ntohs()
uint16_t mg_ntohs(uint16_t net);
Convert uint16_t
value to host order.
Parameters:
net
- 16-bit value in network order
Return value: 16-bit value in host order
Usage example:
uint16_t val = mg_ntohs(0x1234);
mg_ntohl()
uint32_t mg_ntohl(uint32_t net);
Convert uint32_t
value to host order.
Parameters:
net
- 32-bit value in network order
Return value: 32-bit value in host order
Usage example:
uint32_t val = mg_ntohl(0x12345678);
mg_ntohs()
uint16_t mg_htons(uint16_t h);
Convert uint16_t
value to network order.
Parameters:
h
- 16-bit value in host order
Return value: 16-bit value in network order
Usage example:
uint16_t val = mg_htons(0x1234);
mg_htonl()
uint32_t mg_ntohl(uint32_t h);
Convert uint32_t
value to network order.
Parameters:
h
- 32-bit value in host order
Return value: 32-bit value in network order
Usage example:
uint32_t val = mg_htonl(0x12345678);
mg_crc32()
uint32_t mg_crc32(uint32_t crc, const char *buf, size_t len);
Calculate CRC32 checksum for a given buffer. An initial crc
value should be 0
.
Parameters:
crc
- Initial CRC valuebuf
- Data to calculate CRC32len
- Data size
Return value: Calculated CRC32 checksum
Usage example:
char data[] = "hello";
uint32_t crc = mg_crc32(0, data, sizeof(data));
mg_check_ip_acl()
int mg_check_ip_acl(struct mg_str acl, uint32_t remote_ip);
Check IPv4 address remote_ip
against the IP ACL acl
. Parameters:
Parameters:
acl
- an ACL string, e.g.-0.0.0.0/0,+1.2.3.4
remote_ip
- IPv4 address in network byte order
Return value: 1 if remote_ip
is allowed, 0 if not, and <0 if acl
is invalid
Usage example:
if (mg_check_ip_acl(mg_str("-0.0.0.0/0,+1.2.3.4"), c->peer.ip) != 1) {
LOG(LL_INFO, ("NOT ALLOWED!"));
}
mg_url_decode()
int mg_url_decode(const char *s, size_t n, char *to, size_t to_len, int form);
Decode URL-encoded string s
and write it into to
buffer.
Parameters:
s
- String to encoden
- String to encode lengthto
- Pointer to output bufferto_len
- Output buffer sizeform
- If non-zero, then+
is decoded as whitespace.
Return value: Decoded bytes count or negative value on error
Usage example:
char url[] = "eexample.org%2Ftest";
char buf[1024];
mg_url_encode(url, sizeof(url) - 1, buf, sizeof(buf), 0); // buf is now "example.org/test"
mg_url_encode
size_t mg_url_encode(const char *s, size_t n, char *buf, size_t len);
Encode s
string to URL-encoding and write encoded string into buf
.
Parameters:
s
- String to encoden
- String to encode lengthbuf
- Output bufferlen
- Output buffer size
Return value: Number of characters written to buf
Usage example:
char url[] = "example.org/test";
char buf[1024];
mg_url_encode(url, sizeof(url) - 1, buf, sizeof(buf)); // buf is now "example.org%2Ftest"
IO Buffers
IO buffer, described by the struct mg_iobuf
, is a simple data structure
that inserts or deletes chunks of data at arbitrary offsets and grows/shrinks
automatically.
struct mg_iobuf
struct mg_iobuf {
unsigned char *buf; // Pointer to stored data
size_t size; // Total size available
size_t len; // Current number of bytes
size_t align; // Alignment during allocation
};
Generic IO buffer. The size
specifies an allocation size of the data pointed
by buf
, and len
specifies number of bytes currently stored.
mg_iobuf_init()
int mg_iobuf_init(struct mg_iobuf *io, size_t size, size_t align);
Initialize IO buffer, allocate size
bytes.
Parameters:
io
- Pointer tomg_iobuf
structure to initializesize
- Amount of bytes to allocatealign
- Alignsize
to thealign
mem boundary.0
means no alignment
Return value: 1 on success, 0 on allocation failure
Usage example:
struct mg_iobuf io;
if (mg_iobuf_init(&io, 0, 64)) {
// io successfully initialized
}
mg_iobuf_resize()
int mg_iobuf_resize(struct mg_iobuf *io, size_t size);
Resize IO buffer, set the new size to size
. The io->buf
pointer could
change after this, for example if the buffer grows. If size
is 0, then the
io->buf
is freed and set to NULL, and both size
and len
are set to 0.
The resulting io->size
is always aligned to the io->align
byte boundary;
therefore, to avoid memory fragmentation and frequent reallocations, set
io->align
to a higher value.
Parameters:
io
- iobuf to resizesize
- New size
Return value: 1 on success, 0 on allocation failure
Usage example:
struct mg_iobuf io;
mg_iobuf_init(&io, 0, 10); // An empty buffer with 10-byte alignment
if (mg_iobuf_resize(&io, 1)) {
// New io size is 10
}
mg_iobuf_free()
void mg_iobuf_free(struct mg_iobuf *io);
Free memory pointed by io->buf
and set to NULL. Both size
and len
are set to 0.
Parameters:
io
- iobuf to free
Return value: None
Usage example:
struct mg_iobuf io;
// IO buffer initialization
// ...
// Time to cleanup
mg_iobuf_free(&io);
mg_iobuf_add()
size_t mg_iobuf_add(struct mg_iobuf *io, size_t offset, const void *buf, size_t len);
Insert data buffer buf
, len
at offset offset
. The iobuf is expanded
if required. The resulting io->size
is always aligned to the io->align
byte boundary; therefore,
to avoid memory fragmentation and frequent reallocations, set align
to a higher value.
Parameters:
io
- iobuf to add dataoffset
- Offset to add databuf
- Data to addlen
- Data length
Return value: new io
length
Usage example:
struct mg_iobuf io; // Declare buffer
mg_iobuf_init(&io, 0, 16); // Initialise empty buffer with 16 byte alignment
mg_iobuf_add(&io, io.len, "hello", 5); // Append "hello"
mg_iobuf_del()
size_t mg_iobuf_del(struct mg_iobuf *io, size_t offset, size_t len);
Delete len
bytes starting from offset
, and shift the remaining bytes.
If len
is greater than io->len
, nothing happens, so such call is silently ignored.
Parameters:
io
- iobuf to delete dataoffset
- Start offsetlen
- Amount of bytes to delete
Return value: New io
length
Usage example:
struct mg_iobuf io;
mg_iobuf_init(&io, 0, 16); // Empty buffer
mg_iobuf_add(&io, 0, "hi", 2); // io->len is 2, io->size is 16
mg_iobuf_del(&io, 0, "hi", 2); // io->len is 0, io->size is still 16
URL
mg_url_port()
unsigned short mg_url_port(const char *url);
Return port for given URL
Parameters:
url
- URL to extract port
Return value: Port for given URL or 0
if URL doesn't contain port and there
isn't default port for URL protocol
Usage example:
unsigned short port1 = mg_url_port("https://myhost.com") // port1 is now 443 (default https port)
unsigned short port2 = mg_url_port("127.0.0.1:567") // port2 is now 567
mg_url_is_ssl()
int mg_url_is_ssl(const char *url);
Check if given URL uses encrypted scheme
Parameters:
url
- URL to check
Return value: 0
is given URL uses encrypted scheme and non-zero otherwise
Usage example:
if (mg_url_is_ssl("https://example.org") == 0) {
// scheme is encrypted
}
mg_url_host()
struct mg_str mg_url_host(const char *url);
Extract host name from given URL.
Parameters:
url
- a URL string
Return value: host name
Usage example:
struct mg_str a = mg_url_host("https://my.example.org:1234"); // a == "my.example.org"
struct mg_str b = mg_url_host("tcp://[::1]"); // b == "[::1]"
mg_url_user()
struct mg_str mg_url_user(const char *url);
Extract user name from given URL.
Parameters:
url
- URL to extract user name
Return value: User name or empty string if not found
Usage example:
struct mg_str user_name = mg_url_user("https://user@password@my.example.org"); // user_name is now "user"
mg_url_pass()
struct mg_str mg_url_pass(const char *url);
Extract password from given URL.
Parameters:
url
- URL to extract password
Return value: Password or empty string if not found
Usage example:
struct mg_str pwd = mg_url_user("https://user@password@my.example.org"); // pwd is now "password"
mg_url_uri()
const char *mg_url_uri(const char *url);
Extract URI from given URL.
Note, that function returns pointer within url
; there is no need to free() it explicitly
Parameters:
url
- URL to extract URI
Return value: URI or \
if not found
Usage example:
const char *uri = mg_url_uri("https://example.org/subdir/subsubdir"); // `uri` is now pointer to "subdir/subsubdir"
Logging
Mongoose provides a set of functions and macros for logging. The application can use these functions for its own purposes as well as the rest of Mongoose API.
LOG()
#define LOG(level, args)
#define MG_ERROR(args) MG_LOG(MG_LL_ERROR, args)
#define MG_INFO(args) MG_LOG(MG_LL_INFO, args)
#define MG_DEBUG(args) MG_LOG(MG_LL_DEBUG, args)
#define MG_VERBOSE(args) MG_LOG(MG_LL_VERBOSE, args)
Logging macros. Usage example:
MG_INFO(("Hello %s!", "world")); // Output "Hello, world"
mg_log_set()
void mg_log_set(const char *spec);
Set Mongoose logging level.
Parameters:
spec
- String, containing log level, can be one of the following values:0
- Disable logging1
- Log errors only2
- Log errors and info messages3
- Log errors, into and debug messages4
- Log everything
Return value: None
It is possible to override log level per source file basis. For example, if
there is a file called foo.c
, and you'd like to set a global level to 2
(info) but increase log level for file foo.c to debug
, then, a spec
should
look like "2,foo.c=3"
. There could be several comma-separated overrides.
Usage example:
mg_log_set("2"); // Set log level to info
mg_log_set("2,foo.c=3,bar.c=0"); // Set log level to info, with overrides
mg_hexdump()
void mg_hexdump(const void *buf, int len);
Log a hex dump of binary data buf
, len
.
Parameters:
buf
- Data pointerlen
- Data length
Return value: none
Usage example:
mg_hexdump(c->recv.buf, c->recv.len); // Hex dump incoming data
mg_log_set_fn()
void mg_log_set_fn(mg_pfn_t logfunc, void *param);
Redirect logs to a custom function. Parameters:
logfunc
- a pointer to a function that logs a single characterparam
- a parameter for a logging function
Usage example: redirecting logs to syslog.
static void mylog(char ch, void *param) {
static char buf[256];
static size_t len;
buf[len++] = ch;
if (ch == '\n' || len >= sizeof(buf)) {
syslog(LOG_INFO, "%.*s", (int) len, buf); // Send logs
len = 0;
}
}
...
mg_log_set_fn(mylog, NULL);
Filesystem
struct mg_fs
struct mg_fs {
int (*st)(const char *path, size_t *size, time_t *mtime); // stat file
void (*ls)(const char *path, void (*fn)(const char *, void *), void *);
void *(*op)(const char *path, int flags); // Open file
void (*cl)(void *fd); // Close file
size_t (*rd)(void *fd, void *buf, size_t len); // Read file
size_t (*wr)(void *fd, const void *buf, size_t len); // Write file
size_t (*sk)(void *fd, size_t offset); // Set file position
bool (*mv)(const char *from, const char *to); // Rename file
bool (*rm)(const char *path); // Delete file
bool (*mkd)(const char *path); // Create directory
};
enum { MG_FS_READ = 1, MG_FS_WRITE = 2, MG_FS_DIR = 4 };
Filesystem virtualisation layer.
Mongoose allows to override file IO operations in order to support different
storages, like programmable flash, no-filesystem devices etc.
In order to accomplish this, Mongoose provides a struct mg_fs
API to
specify a custom filesystem. In addition to this, Mongoose provides several
built-in APIs - a standard POSIX, FatFS, and a "packed FS" API:
extern struct mg_fs mg_fs_posix; // POSIX open/close/read/write/seek
extern struct mg_fs mg_fs_packed; // Packed FS, see examples/device-dashboard
extern struct mg_fs mg_fs_fat; // FAT FS
struct mg_fd
struct mg_fd {
void *fd;
struct mg_fs *fs;
};
Opened file abstraction.
mg_fs_open()
struct mg_fd *mg_fs_open(struct mg_fs *fs, const char *path, int flags);
Open a file in a given filesystem.
Parameters:
fs
- a filesystem implementationpath
- a file pathflags
- desired flags, a combination ofMG_FS_READ
andMG_FS_WRITE
Return value: a non-NULL opened descriptor, or NULL on failure.
Usage example:
struct mg_fd *fd = mg_fs_open(&mg_fs_posix, "/tmp/data.json", MG_FS_WRITE);
mg_fs_close()
void mg_fs_close(struct mg_fd *fd);
Close an opened file descriptor.
Parameters:
fd
- an opened file descriptor
Return value: none
mg_file_read()
char *mg_file_read(struct mg_fs *fs, const char *path, size_t *size);
Read the whole file in memory.
Parameters:
fs
- a filesystem implementationpath
- a file pathsize
- if not NULL, will contained the size of the read file
Return value: on success, a pointer to file data, which is guaranteed to the 0-terminated. On error, NULL.
Usage example:
size_t size = 0;
char *data = mg_file_read(&mg_fs_packed, "/data.json", &size);
mg_file_write()
bool mg_file_write(struct mg_fs *fs, const char *path, const void *buf, size_t len);
Write a piece of data buf
, len
to a file path
. If the file does not
exist, it gets created. The previous content, if any, is deleted.
Parameters:
fs
- a filesystem implementationpath
- a file pathbuf
- a pointer to data to be writtenlen
- a data size
Return value: true on success, false on error
Usage example:
mg_file_write(&mg_fs_fat, "/test.txt", "hi\n", 3);
mg_file_printf()
bool mg_file_printf(struct mg_fs *fs, const char *path, const char *fmt, ...);
Write a printf-formatted data to a file path
. If the file does not
exist, it gets created. The previous content, if any, is deleted.
Parameters:
fs
- a filesystem implementationpath
- a file pathfmt
- a mg_snprintf format string
Return value: true on success, false on error
Usage example:
mg_file_printf(&mg_fs_fat, "/test.txt", "%s\n", "hi");